1// SPDX-License-Identifier: GPL-2.0
2#include <linux/bpf.h>
3
4#include <bpf/bpf_helpers.h>
5
6struct {
7 __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
8 __uint(max_entries, 3);
9 __uint(key_size, sizeof(__u32));
10 __uint(value_size, sizeof(__u32));
11} jmp_table SEC(".maps");
12
13int selector = 0;
14
15#define TAIL_FUNC(x) \
16 SEC("tc") \
17 int classifier_##x(struct __sk_buff *skb) \
18 { \
19 return x; \
20 }
21TAIL_FUNC(0)
22TAIL_FUNC(1)
23TAIL_FUNC(2)
24
25SEC("tc")
26int entry(struct __sk_buff *skb)
27{
28 int idx = 0;
29
30 if (selector == 1234)
31 idx = 1;
32 else if (selector == 5678)
33 idx = 2;
34
35 bpf_tail_call(skb, &jmp_table, idx);
36 return 3;
37}
38
39char __license[] SEC("license") = "GPL";
40

source code of linux/tools/testing/selftests/bpf/progs/tailcall5.c